The invention relates to a form carrier and actuating device for the machine vulcanizing tires for motor vehicles, which--in comparison to machines having been used up to now for the same purpose--enables the application in a far wider circle by the fact, in so far as it can be rendered suitable for the vulcanizing-pressing tools for tires being different in respect to dimensions. The form constructions having been developed in other plants with exchangeable tread forms, the so-called containers are ordered to one single type of vulcanizing machine, restricting these systems to a narrow range of tire-dimensions.
Inaccuracies occuring in course of production, such as deformations arising while vulcanizing can be eliminated only by disassembling the container, the pre-stress gap required by vulcanizing technology--the role of which will be detailed later--can be adjusted to the desired value exclusively by the subsequent processing of the components of the disassembled container. Among the methods used for closing the form-segments, for radial clamping of the tire to be vulcanized, radial displacement by sliding along the inner surface of the cone-mantle is well known. Such a solution is described in the German Pat. No. 2 254 334 and in the European Patent Application No. 0 170 109.
When closing the vulcanizing form a downwards tending force affects the structural element lying topmost, this force is to be transferred to the segments performing radial clamping of the raw tire so that orientation and clamping should be the possibly best. For this purpose the socalled pre-stress gap used to be applied, that increasing pressure force should attack towards the sliding segments only up to a certain limit and only after having surpassed said limit value the central larger surface of the upper sheet could bear up, when orientation against high friction does not take place anymore. Accordingly, the pre-stress gap will be formed between the parts which lie within the flanges of two structural elements fitting to each other with the upper planar surfaces, whereas critical pressure force closing the gap will be determined by the elastic deformation resulting from the dimensions and material fo the pressed sheet. In case, if the pre-stress gap is too small, due to early closing it may happen more easily that sprues are forming on the tire due to inproper fitting. In case, if the pre-stress gap is too large, the upper form-half may rise due the lifting effect of the vulcanizing pressure, as a consequence, the vulcanized tire will be one sided.
The drawback of the known and presently used equipment lies in that the pre-stress gap can be modified with difficulties only, e.g. by cutting. Gaps of different size are to be ordered to tires of different sizes.